Determination of asphaltic components of petroleum



Oct. 20, 1959 R. B. WILLIAMS ETAL 2,909,432

DETERMINATION OF ASPHALTIC COMPONENTS OF PETROLEUM Filed Nov. 14. 1957CORRELATION BETWEEN ASPHALTENES- CONTENT AND PARA MAGNETIC RESONANCE I'ABSORPTIVITY OF RESIDUA FRACTIONS. I 50 I E Z n I; J g

(I) El Ill 2 50 2 O In Ill 1 2 2o 0 U 2 0 2 Io 0 I0 20 3o 40 so soASPHALTENES CONTENT,WEIGHT PERCENT.

FIG. I.

I I4 L TREATING '7 i ZONE I I 20 v V 1 l H 36 7+ I I I 22 I 2 I ANALYSISZONE SOLVENT i FOR DETERMINING Z ASPHALTENES 32 3o CONTENT I l i A I z Ig INVENTORS. 4 FIG 2 ROLLIE B. WILLIAMS,

RHODERICK K. SAUNDERS,

ATTORNEY.

United States Patent" 071cc DETERMINATION or ASPHALTIC COMPONENTS pPETROLEUM Rollie B. Williams and Rhoderi ck K. Saunders, Baytown,

Tex'., assignors, by mesne assignments, to Esso Research and EngineeringCompany, Elizabeth, N.J.,'a corporation of Delaware pApplicationNovemberM, 1957, Serial No. 696,362

6 Claims. l. 208-309) This invention relates to" a method fordetermining the quantity oflasphaltene type hydrocarbons contained in asira ble feed components for many hydrocarbon treating processes; suchasfhydrocarbon cracking processes, and therefore are desirably excludedfrom the feed stock by suitable means such as fractional distillation,deasphalting, etc.

' Asphaltic hydrocarbon components tend to be insoluble in lighthydrocarbon fractions such as paraflinic naphtha fractions and thereforeas'phaltene hydrocarbon determinations are normally made on the basis oftime-consuming solubility tests. j p

It has been discovered in accordance with the present invention thatwhen an asphaltenes-containin'g petroleum hydrocarbon sample issubjected to electron paramagnetic resonance spectroscopic analysis,there is obtained a sig nal having an intensity responsive to thequantity of asphal-tene components in the sample. The electronparamagnetic resonance spectroscopic determination of the presentinvention iseasily conducted with electron paramagnetic resonancespectrometers of conventional con- 2,909,482 I Pate e 9 tion is madeunder standardized predetermined operating conditions with aspectrometer of predetermined standardized construction whereby theintensity of the signalthat is obtained provides a direct quantitativedetermination of the asphaltenes content of the. samples The determinaation may be made while the sampleis in a solid, semi-solid, or liquidcondition. It is preferable to dilute the. asphaltenes-containing samplewith an amount ,of a. low boiling solvent suflicient to provide asolution containing. a predetermined amount of sample, such amountpreferably being less than about 10% by volume. 1 I

In accordance with a preferred form of the present in.- vention, acontinuous processjfor the treatmentof-an as: phaltenes-containingpetroleum hydrocarbonfraction is regulated by periodically orcontinuouslys'ampling a treat ing process hydrocarbon stream 'bydetermining the as phaltenes content of such samples and by continuouslyregulating a treating process: variable in response to suchdetermination. 1 The present invention -Will.be' further illustrated bythe following specific examples and by the. accompanying drawings whichare given by yvay of illustration and which are not intended aslimitations on the scope of the invention.

In the drawingsy e 7 ;-j Fig. 1 is a graph showing the interrelationshipof electron paramagnetic resonance signal intensity, with respect toasphaltenes content, as. demonstrated by the data of Example I; and p jFig. 2 is a schematic diagram indicating onemanner in which a processfor treating an asphaltic hydrocarbon may be regulated in accordancewiththegpresentyinven tion 7 V f EXAMPLE I A plurality of deasphaltedoil samples and residuum petroleumsamples were subjected to electronparamagnetic resonance spectroscopic analysis on a spectrometer operatedat a frequency of about 9200, megacycles at a magnetic field strength ofabout 3.000 gauss. The samples were contained in thin cylindrical glasstubes of about 5 mm. outside diameter., The samples tested and the re;sults obtained are set forth in Table I. Theresults are furthergraphically presentedin Fig. 1;. I

. p Table I ELECTRON PARAMAGNETIC RESONANCE "DETERMINATIONS OFASPHALTENES I CONTENT H Ooncentra- Aspha1- tion of Peak Height Adjusted2 Sample tenes Sample 111 Prior to Relative Peak 'Absorp No. Nature ofSample Content, Sample Adjustment Attend Height ..tivity Tube, (ChartDiv.) 48171011 (Chart Percent 1 GmsJom Div.) Length West Texas Re- 6. 870. 1109 16. 0 3. 8 60. 8 548 sidiuum.

Deasphalted 0il.-.- 0.08 0. 1132 1. 3 1.0 1. 3 11 -do 0.00 0.1179 2.11.0 2.1 18 Asphalt... 20. 6 0. 0717 36. 3 3. 8 137. 9 1, 923 Deasphalt2. 9 0. 1156 39. 5 1. 0 39. 5 342 Asphalt 59. 8 0. 0801 27. 7 17. 483. 46, 035

1 By standard solubility test.

2 Adjusted peak height= original peak heightxattenuation.

5 Absorptivity= Adjusted peak height Concentration From Table I and Fig.1, it is seen that there is a correlation between electron paramagneticresonance signal intensity and asphaltenes content whereby a directquantitative measurement of asphaltenes content may be made.

The manner in which a petroleum hydrocarbon treating process may beregulated in accordance with the present invention is illustrated withreference to Fig. 2.

Turning next to Fig. 2, there is shown a treating zone for treating anasphaltic petroleum hydrocarbon fraction. Treating zone 10 may be, forexample, a solvent deasphalting zone for deasphalting an asphaltichydro,- carbonfeed stock with a solvent such as a liquefied normallygaseous hydrocarbon, liquefied sulfur dioxide, etc. to obtain adeasphalted oil suitable for catalytic cracking, a distillation zone forseparating an asphaltenes-free distillate fraction from an asphalticfeed stock, a blending zone wherein an asphaltic hydrocarbon fractionderived from a petroleum refining process (e.g., catalytic cracking,distillation, etc.) is blended with a non-asphaltic fuel oil fraction toprovide a furnace fuel, etc.

An asphaltenes-containing hydrocarbon feed stock is charged to thetreating zone 10 by way of a charge line 12 regulated by suitable meanssuch as an electrically or pneumatically actuatable valve 14. Althoughonly a single charge line for the treating zone 10 is shown in Fig. 2,it will be understood that in practice one or a plurality of chargestreams may be charged to the treating zone 10, depending upon theparticular treating process to be conducted therein. A treating proc essproduct stream is discharged from the zone 10 by way of a line 16." Itwill be understood that in many processes a plurality of dischargestreams (not shown) may be discharged from the treating zone 10.

In accordance with the present invention, the product stream 16 issequentially sampled (on an intermittent or continuous basis) by way ofa sample line 18 controlled by a valve 20 leading to an analysis zone22. If desired, a suitable solvent may be blended with the sample in theline 18, the solvent being charged by way of a line 24 controlled by avalve 26.

The sample material, after analysis, may be discharged from the analysiszone by way of the discharge line 30 controlled by a valve 32 fordischarge from the system or alternately, for example, may be returnedto the'discharge line 16 by way of a line 34 controlled by a valve 36.

The electron paramagnetic resonance absorptivity of the samples ismeasured in the zone 22 and a signal constituting a measurement ofasphaltenes content is obtained which is transmitted by way of a lead 28to a suitable process variable control means such as the actuating meansfor the value 14. If the intensity of the signal. transmittedthrough'the lead 26 falls outside of a predetermined signal intensityrange, the setting of the valve 14 will be changed by actuating ofthecontrol means to thereby provide for the desired treating conditionsin the zone 10.

As a specific example, the treating zone 10 may be a deasphalting zonewherein a hydrocarbon residuum fraction is treated with a liquefiednormally gaseous hydrocarbon solvent under conditions of temperature,contact time, and solvent-to-oil ratio sufiicien-t to provide for theobtaining of a deasphalted oil fraction suitable for catalytic crackingand an asphalt fraction.

In a typical solvent deasphalting operation it may be desirable toregulate deasphalting operations in a manner to provide for the presenceof from about 0.1 to 1 weight percent of asphaltenes in the deasphaltedoil, this being done in order to insure the recovery of a maximizedamount of useful non-asphaltic components or to exclude a maximizedamount of asphaltic components. In this situation, the asphaltenescontent of the discharge stream 16 is sequentially determined (onacontinuous or intermittent basis) and if the asphaltenes content fallseither above or below the predetermined range, a deasphalting processvariable may be altered in response to determination to provide for thedesired asphaltenes content. Among the deasphalting process variablesthat may be regulated are solvent-to-feed stock ratio, temperature,solvent composition, etc.

Having described our invention, what is claimed is:

1. A method for determining the asphaltenes content of an asphalticpetroleum hydrocarbon sample which comprises measuring the electronparamagnetic resonance absorptivity of said sample to thereby obtain ameasurement of the asphaltenes content of said sample.

2. A method 'for determining the asphaltenes content of an asphaltichydrocarbon sample which comprises dissolving said sample in a non-ionicorganic solvent and then measuring the electron paramagnetic resonanceabsorptivity of said sample to thereby obtain a measurement of theasphaltenes content of said sample.

3. In a process for continuously treating an asphaltic hydrocarbon feedstock, the improved method for regulating said treating process whichcomprises the steps of sequentially sampling a treating process stream,sequentially measuring the electron paramagnetic resonance absorptivityof the thus-obtained samples under predetermined analysis conditions andcontrolling a hydrocarbon treating process variable in response to saidmeasurement.

4. A process as in claim 3 wherein the treating process is a solventdeasphalting process. v

5. In a process wherein an asphaltic petroleum hydrocarbon feed stock isdeasphalted by contact with a liquefied normally gaseous hydrocarbon toseparate said feed stock into an asphaltic fraction and a deasphaltedoil fraction, the improved method for regulating said deasphaltingoperation which comprises the steps of sequentially sampling saiddeasphalted oil fraction, sequentially subjecting said samples toelectron paramagnetic resonance spectroscopic analysis to obtain anelectrical signal constituting a measurement of the asphaltenes con tentof said samples and electrically regulating a deasphalting processvariable in response to said signal.

6. A process as in claim 5 wherein the ratio of liquefied normallygaseous hydrocarbon to asphaltic feed stock is regulated in response tothe signal.

Alway et al. Oct. 26, 1954 Kirshenbaum Oct. 2, 1956

1. A METHOD FOR DETERMINING THE ASPHALTENES CONTENT OF AN ASPHALTICPETROLEUM HYDROCARBON SAMPLE WHICH COMPRISES MEASURING THE ELECTRONPARAMAGNETIC RESONANCE ABSORPTIVITY OF SAID SAMPLE TO THEREBY OBTAIN AMEASUREMENT OF THE ASPHALTENES CONTENT OF SAID SAMPLE.